Taxonomic information across the Internet

Spionidae

This questionnaire deals with describing specimens of the
family Spionidae Grube 1850. Spionids are common members of soft-sediment communities and
are particularly species rich. For example, they account for 12.8% of all polychaetes
collected off the west coast of Phuket Island in Thailand (Hylleberg & Nateewathana,
1984. Proceedings of the First International Polychaete Conference. Linnean Society of New
South Wales).

What does a spionid look like?

Pygospio elegans - a spionid worm

Spionids are elongated worms. The body regions are not
rigidly distinct but can be differentiated by changes in the shape of the parapodia and
types of setae. They use two long palps to carry food to the mouth, (sometimes called
tentacles) which arise on the peristomium. Unfortunately, the palps have a tendency to
drop off when the animal is fixed. The prostomium is variable in shape between genera and
species, so it is a good taxonomic character. Branchiae or gills are found in most genera
and their distribution is also a taxonomic character. Again branchiae break off when the
animal is fixed unless care is taken to relax the specimen first. Parapodia are biramous,
possessing a dorsal notopodium and ventral neuropodium. Setal types include simple
capillaries, thickened sabre setae and hooks (which may be hooded).

What other families could be confused with the
Spionids?

Heterospionidae. Superficially, specimens
of this family may resemble spionids. They have a similar shape of body and long feeding
palps arising from the peristomial region. There are distinct differences: the anterior
part of the body possesses long filiform branchiae or gills which are more like those
found on cirratulids, the setae of posterior segments form nearly complete rings around
the segment, most of the setae are simple capillaries. (See Heterospionidae in the Family Browser)

Trochochetidae. This family possesses
species with distinct body regions and there are three processes projecting from the
prostomial region. The neuropodia of the first setiger (the first segment bearing setae)
are long and project forwards forming an open mesh around the head. (See Trochochaetidae in the Family Browser)

Chaetopteridae. Apart from the very
distinctive Chaetopterus variopedatus, other species can superficially resemble
spionids. They can be distinguished by the lack of neuropodial (ventral) setae, by the
presence of enlarge setae on setiger 4, distinctly lobed posterior notopodial lobes and a
distinctive enlarged mouth region, and the presence of neuropodial uncini. (See Chaetopteridae in the Family Browser)